/Engine/Source/Editor/UnrealEd/Public/EdGraphUtilities.h
Moves the contents of all of the children graphs of ParentGraph (recursively) into the MergeTarget graph. This does not clone, it's destructive to the ParentGraph
static void MergeChildrenGraphsIn ( [UEdGraph](API\Runtime\Engine\EdGraph\UEdGraph) * MergeTarget, [UEdGraph](API\Runtime\Engine\EdGraph\UEdGraph) * ParentGraph, bool bRequireSchemaMatch, bool bInIsCompiling, [FCompilerResultsLog](API\Editor\UnrealEd\Kismet2\FCompilerResultsLog) * MessageLog )